Fabrication of MnFe2O4 spheres modified CeO2 nano-flakes for sustainable photodegradation of MB dye and antimicrobial activity: A brief computational investigation on reactive sites and degradation pathway

The synthesis of CeO2/MnFe2O4 NCs has been carried out by ultrasonication-assisted co-precipitation method. Transmission electron microscopic (TEM) analysis confirmed the embedment of MnFe2O4 over CeO2 with clear lattice fringes. Energy dispersive analysis (EDAX) and elemental mapping confirm the existence of elements including Ce, Mn, Fe, and O. The XRD patterns of the NCs indicated the effective construction of crystalline CeO2/MnFe2O4 NCs with the co-existence of CeO2 and MnFe2O4 in desired molar ratio. The degradation rate constant of CeO2/MnFe2O4 NCs-1:1 under visible light illumination was estimated to be 0.0108 min(-1), which was 2.2 and 2.8 times greater than CeO2 and MnFe2O4 respectively. Here, the study provides a clear insight into the photocatalytic mechanism of the p-n type NCs, which exhibited efficient charge transfer and improved mobility. The scavenging assay and ESR analysis have explicated the major role of .OH radicals as the dominant reactive oxygen species on the photocatalytic degradation of MB dye. The photocatalytic efficiency of CeO2/ MnFe2O4 NCs-1:1 for MB dye degradation was found to be 86%. The results expressed almost similar degradation efficiency till the 6th cycle and the structural integrity of the NCs was found to be intact even after the photo-degradation. Additionally, a predictive degradation pathway for MB was elucidated by Fukui function-based DFT analysis. The anti-microbial activity of the prepared samples was investigated against S. aureus and E. coli. Hence, the fabricated CeO2/MnFe2O4 NCs-1:1 was concluded with the obtained results and it has been observed to be a potential candidate as an efficient photocatalyst for the elimination of toxic organic pollutants.

Automated summary

CeO2/MnFe2O4 nanocrystals were successfully synthesized and characterized in this study. The nanocrystals exhibited high degradation efficiency under visible light illumination and showed excellent charge transfer and mobility. The study also elucidated the major reactive oxygen species in the photocatalytic degradation of MB dye and evaluated the antimicrobial activity of the prepared samples.